Method and apparatus for explosive reshaping of hollow ductile objects



c. E. MAIER 3,252,312 METHOD AND APPARATUS FOR EXPLOSIVE RESHAPING OFHOLLOW DUCTILE OBJECTS May 24, 1966 4 Sheets-Sheet 1 Filed April 25,1962 Ex H A 0 ST INVENTOR ATTORNEYS a I m .3 1. a, 5 r2 g 5 a 7 6 7 k 8A m I 4 7 i U x G 7 2 Y\\\\\ C 4 2 E V an 2 2 5 m 3 A.

1 s 4 e z r J L L m 6 T h May 24, 1966 c. E. MAIER 3,252,312

METHOD AND APPARATUS FOR EXPLOSIVE RESHAPING OF HOLLOW DUCTILE OBJECTSFiled April 25, 1962 r 4 Sheets-Sheet '2.

Ill,

INVENTOR Curzns E. MAIEE.

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ATTORNEYS May 24, 1966 c. E. MAIER 3,252,312

METHOD AND APPARATUS FOR EXPLOSIVE RESHAPING OF HOLLOW DUCTILE OBJECTSFiled April 25, 1962 4 Sheets-Sheet 4 7 5 I 4 F 5 I 1 A INVENTOR Cuz-nsE. MAnzz ATTORNEYS York Filed Apr. 25, 1962, Ser. No. 190,029

20 Claims. (Cl. 7256)' This invention relates in general to new anduseful improvements in the manufacture of hollow ductile objects, andmore particularly to a novel method of reshaping hollow ductile objectsand the apparatus for accomplishing such reshaping.

Hollow objects are readily produced in quantity when the shapes of suchobjects are regular. This is particularly true when the objects are ofconstant cross section or tapered. However, when the cross section of anobject is varied or the surface of the object is specially configurated,such as by embossing, the forming operation becomes very expensive andheretofore has not been feasible for production in large quantities. Inaccordance with this invention it is proposed to form specially shapedhollow objects by first forming regular shaped articles of ductilematerials by relatively inexpensive conventional forming operations, andthereafter reshaping the regular shaped articles by an explosive formingoperation which also maybe carried out at a relatively low cost,

This invention has a primary application with respect to objects formedof ductile metals, particularly those made from steel, both coated anduncoated including metal coated steel, such as tin-coated steel,aluminum, etc. However, the invention is not restricted to the shapingof ductile metal objects in that the principles of the invention mayequally as Well be applied to intricately-shaped plastic objects whereinthe plastic material is of the ductile type. Although polyethylene hasproven to be most desirable plastic at the present, other types ofplastics could be utilized, including polyvinyl chloride, polypropylene,polycarbonates, etc.

In accordance with the invention, the hollow articles which may bereshaped generally fall into three categories as follows: (1) hollowarticles open at opposite ends; (2) hollow articles each having one endonly thereof closed either by an integral end member or a separate endmember attached by any means including welding and crimping; and (3)hollow articles having end members at opposite ends thereof with one ofthe end members being either integral or attached by any means includingwelding and crimping and the other end member being attached by anymeans including welding and crimping, but with one of the end membershaving a large enough hole to permit filling the object with anexplosive gas mixture and the insertion of detonating means. When anarticle is provided with one or more end members at the time of thereshaping thereof through explosive forming, it is also possible toreshape the end member.

The invention is readily adaptable to numerous types of objects orarticles, but finds particular advantages in the field of containerswhich are mass produced in regu-- ject of this invention to providecontainers of all commonly used sizes, including commercially useddrums, for example 55 gallon drums, wherein the containers have UnitedStates Patent been reshaped from existing and newly deviced regularshapes to be of the desired configuration.

Metal cans up to one gallon in capacity are at the present time producedat a minimum cost on existing high speed fully automatic can makingequipment at the rate of 200 to over 1000 cans per minute. However, toso produce these metal cans, the shape of the side walls of the' canbodies is relatively straight-sided, simple, cylindrical, square oroblong, although it is possible for the can bodies to be tapered, and ina separate unit operation, the top and bottom ends must be manufacturedand attached to the previously made can bodies, one end before, and theother end after the product for which the can was manufactured is filledinto the can. Cans produced by such a method have the side wells joinedat a side seam, which for the majority of products that are to becontained, must be secured either by welding, by soldering, or byapplying organic sealing cements tailored to the particular product, thestrength of which side seam joints decrease rapidly in the ordermentioned.

Metal cans are also produced with integral bottoms, and without a sideseam joint, by a single or multiple drawing or by extrusion methods, butat slower speeds, the speed being approximately 100 cans per minute.These cans are also formed at a greater cost than the customarythree-piece round, square or rectangular cans made by the high speed,fully, automatic method.

On the other hand, glass and conventionally molded plastic containers,while produced at much lower speeds than the three-piece metal cans madeon the high speed, fully automatic equipment, may have practically anyshape that the customer desires,

Although a majority of products will continue to be packaged in thecustomary three-piece straight line containers, there is an increasingdemand by the packaging industry for ornamental containers which cannotbe filled by the present container manufacturing equipment and whichrequire that the packaging industry draw upon glass and conventionallymolded plastic containers where the cheaper ductile containers couldotherwise be used. It is therefore the primary object of this inventionto provide an inexpensive method of reshaping or reforming the ductilecontainers wherein not only the cross section of a container may bevaried from the customary cylindrical cross-section, but also thesurface of the container may be irregularly shaped to the desiredornamental pattern so as to meet the requirements of the packagingindustry.

Another object of this invention is to provide a novel method ofreshaping ductile containers which is readily adaptable to a productionline, the method of reshaping the containers including the clamping of acontainer within a mold with the ends thereof sealed, after which anexplosive mixture of gases is exploded within the sealed container andthe resultant gas pressure shock wave will effect the outward expansionof the container in accordance with the configuration of the mold inwhich the container is disposed.

Another object of this invention is to provide a novel method ofreshaping containers to desired ornamental configurations includingirregular cross-sections, the method of reshaping the containers beingof a nature wherein the containers may be continuously delivered byconveyor means and the reshaping takes place at a station along aconveyor so that the method is readily adaptable to existing productionlines.

Still another object of this invention is to provide a novel method ofquickly reshaping a cylindrical or other straight line container todesired ornamental configuration with a minimum of cost by the clampingof the container within a configurated mold and introducing into thecontainer an inexpensive combustible gas mixture which, when ignited,will explode and the pressure shock wave resulting therefrom willproduce the necessary force to effect the drawing of the container tothe desired configuration which is determined by the shape of the mold.

A further object of this invention is to provide a novel method ofreshaping can bodies which is readily adaptable to existing canproduction lines and which may be accomplished at a minimum of expense,the method being suitable for conveyor line operation and operating toremove a can body from a conveyor line of the indexing type and duringthe stationary portion of the cycle of operation of the conveyor, thecan body may be submitted to a device which will effect the explosion ofcombustible gases within the can body and effect the outward flowing ofthe can body due to the force of a pressure shock wave resulting fromthe explosion so that the can body will as sume a configurationcorresponding to that of the mold in which it is seated.

Still another object of this invention is to provide a novel method ofreshaping can bodies, which method is suitable to can bodies which havebeen formed with high strength side seams of the solder type, withwelded side seams and those of the seamless type, the method also beingadaptable to either can bodies without ends or can bodies with one endattached thereto.

Another object of this invention is to provide a novel can body whichhas been reshaped to have an ornamental surface configuration andwherein the reshaping has been accomplished within a mold by theexplosion of combustible gases sealed within the can body.

Still another object of this invention is to provide a novel method ofreshaping cylindrical and like straight sided can bodies to have desiredornamental cross-sections and surface configurations, the methodutilizing the pressure shock wave resulting from explosion of gases andbeing suitable for use in conjunction with both plain can bodies and canbodies having one end attached thereto.

A still further object of this invention is to provide a novel apparatusfor effecting the reshaping of can bodies utilizing the pressure shockforce resulting from the explosion of combustible gases, the apparatusbeing of the type wherein a can body may be removed from a line of'conveyed cans during the stationary period between indexirig of theline, the apparatus then taking the removed can body and sealing theends thereof within a split mold receiving the can body, and theapparatus further effecting the shaping of the can body within the splitmold when an explosive gas mixture is ignited within the can body.

Yet another object of this inventionis to provide a novel method offorming a shaped and decorated container or like object having alithographed surface, the method including the steps of forming a basiccontainer shape which is lithographed in accordance with thepredeter-mined intended final shape either prior to or subsequent to theforming thereof, and explosively reforming the basic container shape andwith the accompanied stretching of the lithographing without damagethereto.

With the above, and other objects in view that will herein after appear,the nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawings:

In the drawings:

FIGURE 1 is a schematic view with parts broken away and shown insection, showing the general details of the apparatus for removing a canbody from a conveyed line of can bodies and effecting the reshaping ofthe can body.

FIGURE 2 is a fragmentary elevational view showing a portion of theapparatus of FIGURE 1, with the can body being initially engaged by acentering support therefor.

FIGURE 3 is a fragmentary schematic elevational View showing a portionof the apparatus of FIGURE 1 with the can body entering into the mold ofthe apparatus.

FIGURE 4 is a fragmentary vertical sectional view showing the can bodyfully seated and locked within the mold and air within the can bodybeing withdrawn therefrom.

FIGURE 5 is a schematic view showing the introduction of a combustiblegas into the can body.

FIGURE 6 is a view similar to FIGURE 5 and shows the introduction ofoxygen into the can body.

FIGURE 7 is a schematic view showing the igniting of the combustible gasand oxygen mixture.

FIGURE 8 is a schematic elevational view similar to FIGURE 1 and showsthe mold in its open position and the can body being lowered out of themold.

FIGURE 9 is a fragmentary vertical sectional view showing a modifiedform of support for supporting and centering can bodies having ends onthe lower ends thereof.

FIGURE 10 is a chart showing the maximum theoretical explosive pressureof various fuels with oxygen and air at different charging pressures.

FIGURE 11 is a chart showing the theoretical maximum explosive pressurefor methane and various oxygen and air to fuel ratios.

FIGURE 12 is a chart showing the maximum rate of pressure rise ofdifferent fuels combined with oxygen for different pressure charging.

FIGURE 13 is a chart showing the maximum rate of pressure rise ofdifferent fuels mixed with air for different charging pressures.

FIGURE 14 a is perspective view of a container body formed in accordancewith the invention starting with a cylindrical body.

FIGURE 15 is a fragmentary vertical sectional view taken along the line15-15 of FIGURE 14 and shows the specific shape of the container body ofFIGURE 14 and the embossing thereof.

FIGURE 16 is a perspective view of a container formed in accordance withthe invention starting with a rectangular cross sectional body.

FIGURE 17 is a fragmentary vertical sectional view taken along the line17-17 of FIGURE 16 and shows the specific shape of the container ofFIGURE 16 and the embossing thereof.

FIGURE 18 is a fragmentary vertical sectional view similar to FIGURE 17and through only an upper part of a slightly modified container whereinthe embossing has been replaced by debossing.

Referring now to the drawings in detail, it will be seen that there isillustrated in FIGURES 1 through 8 a schematic showing of a step-by-stepoperation of reshaping a container in accordance with this invention.Although hereinafter reference will be made to the reshaping of a can,it is to be understood that various types of containers may be shapedand the invention is in no way restricted to cans. Referring first toFIGURE 1, it will be seen that there is illustrated a support 15 alongwhich can bodies 16 are moved with the can bodies 16 being disposed inspaced relation. It is preferred that the can bodies 16 be deliveredalong the support 15 in a step-bystep manner in order to provide thenecessary time for the reshaping operation, although if desired, the canbodies 16 could be continuously supplied and means could be provided forpresenting a single can body to the reshaping mechanism upon demand.

In according with the invention, the support 15 is provided with amounting block 17 in which there is seated a support member 18 adaptedto be vertically lifted out of the mounting block 17. In addition tobeing seated within the mounting block 17, the support member 18 iscarried by a vertically reciprocating plunger 19 for movement therewith.The plunger 19 has an upper end closure 26 and is provided adjacent theupper end thereof with an outwardly directed flange 21. -The sup portmember 18 is provided with an internal recess 22 in which the flange 21is received. The recess 22 has a greater vertical extent than the flange21 so that upon initial upward movement of the plunger 18, there will beno movement of the support member 18 so that the upper end of theplunger 19 may enter into a can body 16 to assure the supporting andalignment of the can body 16 with the support member 18. After a slightinitialupward movement of the plunger 19, the flange 21 engages theportion of the support member 18 defining the upper end of the recess 22and the support member 18 is moved upwardly together with the plunger19. At this time, it is pointed out that the plunger 19 may be movedupwardly in any desired manner, including the plunger 19 being part of afluid motor.

Another support 23, which has been schematically illustrated, overliesthe support and carries a clamp plate 24 which is disposed in alignmentwith the support member 18. The clamp plate 24 has a depending centralportion 25 which serves to guide the upper end of a can body 16 toassure the proper alignment of the can body 16 with the clamp plate 24.The underside of the clamp plate 24 surrounding the depending centralportion 25 is provided with a suitable sealing ring 26 which isengageable with the upper end of the can body 16 to effect the sealedclosing of the can body 16. The.support member 18 will have a similarsealing ring 27 on the upper surface thereof for engaging and sealingthe lower end of the can body 16.

The clamp plate 24 is provided with a suitable igniter 28 which may bein the form of a spark plug or any other suitable type of igniter. Theigniter 28 is provided with suitable spaced posts 29 which arepreferably positioned so as to be disposed centrally of the can body 16when the can body 16 is engaged with the clamp plate 24.

The clamp plate 24 is also provided with a pipe 30 which extends throughthe clamp plate 24 and is suitably threaded therein, as at 31. The pipe30 will be used for the purpose of exhausting a can body and supplyingthe necessary materials of combustion thereto inthe performance of areshaping operation.

The support 23 has a pair of depending brackets 32 of which only one isshown. Each depending bracket 32 carries a fluid motor. 33 of the doubleacting type with each fluid motor 33 including an extensible plunger 34which, in turn, supports a mold half 35. The two mold halves 35 arepreferably identical, and the mold halves 35 are provided with internalconfigurations 36 corresponding to the desired final shape of a canbody.

The pipe 30 leads to a rotating valve assembly, generally referred to bythe numeral 37. The valve assembly 37 includes a housing 38 and arotating valve member 39. The valve member 39 is only schematicallyillustrated, but it is to be understood to have a fixed port 40 which iscontinuously aligned with the pipe 30. The valve member 39 also has arotating port 41 which is in continuous communication with the port 40.

In addition to the pipe 30 secured to the valve housing 38, there is apipe 42 which is secured to a suitable vacuum source and will beconsidered a vacuum line. A pipe 43 is connected to the housing 38 forsupplying a combustible gas under pressure to the valve 37. A pipe 44 issecured to the housing for delivering to the valve 37 an oxidizingagent, such as air or oxygen under pressure. A further pipe 45 isconnected to the atmosphere. It is to be noted that the pipes 30, 42,43, 44 and 45 are equally spaced about the circumference of the valvehousing 38 with the exception that there is a spacing skipped betweenthe pipes 44 and 45, there being no pipe in diametrically oppositerelation with respect to the pipe 42. In accordance with the invention,it is intended that a suitable spark control device be associated withthe valve 37 and when the valve 37 is positioned at the stationintermediate the pipes 44 and 45, the spark device will serve toenergize the igniter 28 for a purpose to be described hereinafter.Although the valve 37 may be continuously rotated, it is preferred thatthe rotation of the valve 37 be on a step-by-step basis in order toprovide sufiicient time for the flow of gases through the various pipes.

Referring now to FIGURE 2 in particular, it will be seen that after acan body 16 has been aligned generally with the support member 18, theinitial upward movement of the plunger 19 will result in the upper endof the plunger 19 entering into the lower end of the associated can body16 and the centering of the can body 16 with respect to the supportmember 18.

Referring now to FIGURE 3, it will be seen that as the plunger 19continues its upward movement, the flange 21 will serve tolift thesupport member 18 and that the support member 18 will engage the lowerend of the can body 16. The can body 16 is illustratedin FIGURE 3 asbeing moved between the spaced apart mold halves 35. At this time, thevalve 37 is in its EXHAUST position.

The continued upward movement of the plunger 19 results in the upper endof the can body 16 engaging the sealing ring 26 of the clamp plate 24.In the event there should be any slight misalignment of the can body 16with respect to the clamp plate 24, the downwardly projecting portion 25of the clamp plate 24 will automatically realign the can body 16. Afterthe can body 16 has been tightly clamped against the underside of theclamp plate 24 so that the upper and lower ends of the can body 16 aresealed, the mold halves 35 are moved together about the can body 16 toprovide a continuous mold about the can body 16. It is to be understoodthat the termination of the upward movement of the plunger 19 and theclosing of the mold halves 35 will be effected by automatic mechanismwhich may be of any conventional type, including a trip lever actuatedby the plunger 19, and the details of such mechanism are not anessential feature of this invention.

After the ends of the can body 16 have been sealed and the mold halves35 moved to their closed positions, the valve member 37 is moved to itsVACUUM position wherein'a vacuum is drawn through the pipe 30 so as toremove a major portion of the air trapped within the can body' 16. Afterthe removal of this excess air has been accomplished, the valve 37 isrotated to its COMBUS- TIBLE GAS position wherein a combustible gasunder pressure is delivered to the interior of the can body 16 throughthe pipe 30. This is best shown in FIGURE 5.

Referring now to FIGURE 6, it will be seen that the valve 37 has thevalve member 39 thereof rotated to the OXYGEN position. Although it hasbeen indicated that oxygen will be delivered to the valve 37 through thepipe 44, it is to be understood that any type of oxidizing agent may bedelivered to the valve 37 through the pipe 44 and that in many instancesin lieu of using oxygen, air will be delivered to the valve 37 throughthe pipe 44. The compressed air, oxygen or other oxidizing agent isdelivered into the interior of the sealed can body 16 to mix with thecombustible gas already delivered to the interior of the can body 16.

Reference is now made to FIGURE 7, wherein the igniter 28 is illustratedin the act of igniting and exploding the combustible gas mixturedisposed within the can body 16. When the combustible gas mixtureexplodes, there will be a rapid increase in pressure within the can body16, and while the extremely high pressure within the can body 16 has atendency to deform the can body 16 outwardly to conform to the shape ofthe mold halves 35, it has been found that the shock wave caused by thehigh burning rate is the primary cause of the shaping of the metalthrough its plastic range to a very much greater elongation than wouldbe possible by more slowly applied forces.

Referring now to FIGURE 8, it willbe seen that the plunger 19 is in theprocess of moving downwardly after the reshaping of the can body 16. Itis to be understood that prior to the separation of the mold halves 35,and the downward movement of the plunger 19, the valve 37 will havemoved to the EXHAUST position wherein the high pressure within the canbody 16 will be released. The can body 16 will continue to move downwith the plunger 19 until the support member 18 is seated within. themounting blocks 17. At this time, the can body 16 will be moved alongthe support 15 to the right, and will be replaced by another can body 16to be reshaped.

While the can body 16 illustrated in FIGURES 1 through 8 is of acylindrical configuration, it is to be understood that the can body 16could be of a square, oval or other conventional straight sidecross-section including being tapered. Also, although only one shapingof the can body 16 has been specifically illustrated methodwise, it isto be understood that the can body 16 may be reshaped to any one ofnumerous ornamental designs and that the shape illustrated in FIGURES 7and 8 is for illustrationv purposes only, as is clearly apparent byreference to FIGURES 14' through 18 which will be described hereinafter.

Although in many instances the can body will be reshaped prior to theplacing of an end thereon, in some instances, it may be desired to placean end, such as the end 46 of FIGURE 9, on the can body 16.

In order to handle a can body having an end, such as the end 46,disposed thereon, it is necessary that a slight mordification be made inthe supporting structure for the can body. To this end, in lieu of thesupport member 18, a support member 47 is shown seated in the mountingblock 17 in FIGURE 9. The support member 47 has an internal recess 48 inthe lower portion thereof in which a flange 49 projecting externallyfrom the plunger 50 is seated. The upper end of the plunger 50 is openand a shaft 51 is disposed therein. The shaft 51 is provided with anenlarged head 52 which overlies the upper end of the plunger 51 and isseated in a recess 53 formed in the upper part of the support member 47.The upper surface of the head 52 is disposed flush with the uppersurface of the support 15 to permit the can body 16 to slide thereonduring the conveying of the can body 16. The shaft 51 and the head 52are held in the upward position by means of a pin 53 which extendsthrough a slot 54 in the plunger 50 and rests upon a suitable stop 55disposed externally of the plunger 50 when the plunger 50 is in itslowermost position. When the plunger 50 is moved upwardly, the head 52stays stationary while the plunger 50 and the support member 47 moveupwardly with the support member 47 passing around the lower portion ofthe can body 16 in the area of the seam 56 between the can end 46 andthe can body 16. After a slight initial upward movement of the plunger50 and the support member 47, the head 52 will be engaged by the plunger50 and the support member 47 to move the head 52 and the can body 16seated thereon upwardly. The remainder of the apparatus illustrated inFIGURE 1 through 8 will be used in conjunction with the apparatus of.FIGURE 9.

When no reshaping of the can end 46 is desired, the upper surface of thehead 52 will be flat or will otherwise be configurated to conform to theshape of the can end 46. On the other hand, when it is desired toreshape the can end, the upper surface of the head 52 will beconfigurated as is indicated at 57, for example. In the event the can 16has a second or upper end (not shown) the underside of the clamp plate24 will be suitably configurated either'to match the upper end of thecan or to conform to the desired configuration to which the upper end isto be reshaped.

Reference is now made to FIGURES 14 and 15 wherein there is illustrateda modified form of can body, generally referred to by the numeral 60.The can body 60 has flanges 61 and 62 at the opposite end thereof forfaciliating the attachment of can ends. The can body 60 wasorigin'allycylindrical prior to the reshaping thereof and may have either a weldedseam or a conventional soldered seam. The can body 60 has a plurality ofvertically spaced, smoothly convexly curved body portions 63 integrallyconnected together by narrow, more sharply curved, concavely curved bodyportions 64. In addition, at least the upper one of the body portions 63has designs 65 embossed thereon, the designs 65 being shown as stars,but being variable as desired. The can body 60 will be provided with canends, either by welding or crimping, one before filling and the otherafter filling.

In FIGURES 16 and 17, there is illustrated another example of acontainer which may be inexpensively formed in accordance with theinvention, the container being generally referred to by the numeral 66.The container 66 is initially constantly square in cross section and hasan end 67 secured to the lower end thereof while still of the squarecross section. It is to be noted that the upper portion 68 of thecontainer 66 has not been enlarged although the central portion 69theroef has been outwardly bowed and the lower portion 70 tapersdownwardly to the end 67. The upper portion 68 terminates at the upperend thereof in a flange 71 for the later attachment of a second end (notshown). Although the upper portion 68 has not been increased in crosssection, the upper portion 68 has been provided with suitable decorativembossing 72.

In FIGURE 18, there is illustrated a modification of the container 66,the container of this figure being referred to by the numeral 73 andhaving an upper portion 74 which corresponds to the upper portion 68.However, the upper portion 74 has decorations which include embossedportions 75 and debossed portions 76.

It is to be understood that the can bodies may be lithographed orotherwise decorated prior to the explosion reshaping thereof, it beingpossible to accurately determine the stretching of the various portionsof the can bodies or like containers and to predecorate accordingly. Itis also to be understood that while the invention has been specificallydescribed with respect to cans, the invention The invention may also bepracticed with plastic containers and like objects. At the present timethe commercially accepted way of forming plastic articles is to extrudea thick walled tube of small diameter and to blow the tube in a mold.This process is a slow one and there is an undue thinning of the plasticat areas of maximum stretching. Further, if the plastic container is tobe provided with metal ends, the ends of the plastic container must betrimmed after the molding thereof. In accordance with this invention, itis proposed to extrude thin wall plastic tubing and to explosivelyreshape the same. This can be quickly and inexpensively accomplishedwhile holding the thinning of the plastic material to a minimum. Theextruded tubing may be of any desired cross section. When the plasticcontainer is to be provided with metal ends, the ends are applied priorto the explosive reshaping of the plastic, thereby eliminating thenormal trimming of the ends of the plastic member.

The primary test conducted with respect to this matter has utilized amixture of city gas and air. The city gas utilized was of approximately1,000 B.t.u. per cubic foot heat content, and from an economicalstandpoint, in many instances, this particular gas mixture may prove themost economically feasible. On the other hand, as is clearly indicatedby the graphs, a much greater effect may be obtained utilizing a mixtureof acetylene and oxygen. The graphs show the results obtainable with thevarious hydro-carbons mixed with either oxygen or air, as well as acombustible mixture of hydrogen and either oxygen or air. A hydrogenoxygen or air mixture provides a very cleanly burning fuel and may be adesirable mixture, although the maximum available explosive pressureutilizing hydrogen is not as great as that obtainable with thehydro-carbons tested. On the other hand, as is clearly' indicated in thegraphs of FIGURES 12 and 13, hydrogen produces a very high maximum rateof pressure rise and is second as compared to acetylene of the gasestested. It was found during testing that the deformation of the can bodywas not dependent primarily on the maximum available pressure as aresult of the explosion, but upon the pressure shock wave, and this isborne out by a comparison of the graphs of FIGURES l and 12, forexample. The results obtainable with hydrogen were very good, althoughthe maximum available explosive pressure utilizing hydrogen was muchlower than that available with the tested hydrocarbons.

Although some gas mixtures may produce much better results than othersfor complicated reshaping of can bodies, where the reshaping isrelatively mild, it will, of course, be economically feasible to utilizegas mixtures which produce much less pressures and have lower rates ofpressure rise in that these will not be necessary and will not requirethe more expensive gases.

The ability to deform and reshape a container on an economicallyfeasible basis is a great advance in the container manufacturing art inthat it now permits a manufacturer of containers to provide economicallycontainers which have ornamental configurations comparable to theornamental configurations of containers formed of glass andconventionally molded plastic. At the same time, the comparable cost ofthe ornamental containers 'with respect to conventionally molded plasticand glass containers will be much less, so that the packaging industrymay now have available inexpensive decorated containers as compared tothe relatively expensive glass and conventionally molded plasticcontainers.

Although preferred embodiments of the invention have been illustratedand described herein, it is to be understood that the invention is notlimited to the specific structures disclosed or to the exact methodsteps set forth with respect to the disclosed structures, and minormodifications may be made in the invention without departing from theinvention within the scope and spirit of the appended claims.

I claim:

1. A method of reshaping tubular bodies comprising the steps ofenclosing an open ended tubular body within a shaped mold and sealingthe ends of the tubular body, delivering an explosive gas mixture intothe interior of the sealed body, and then igniting the gas mixture andthereby producing a products of combustion pressure shock wave whichoutwardly expands the tubular body to conform to the shape of the mold.

2. A method of reshaping tubular bodies comprising the steps ofenclosing a tubular body 'within a shaped mold and sealing the ends ofthe tubular body, delivering an explosive gas mixture under a pressurein excess of atmospheric pressure into the interior of the sealedtubular body, and then igniting the gas mixture and thereby producing aproducts of combustion pressure shock wave which outwardly expands thetubular body to conform to the shape of the mold.

3. A method of reshaping tubular bodies comprising the steps ofenclosing a tubular body within a shaped mold and sealing the ends ofthe tubular body, delivering an explosive gas mixture under a pressurein excess of atmospheric pressure but insufiicient to shape the tubularbody into the interior of the sealed tubular body, and then igniting thegas mixture and thereby producing a products of combustion pressureshock wave which outwardly expands the tubular body to conform to theshape of the mold.

t 4. A method of reshaping tubular bodies comprising the steps ofenclosing a tubular body within a shaped mold and sealing the ends ofthe tubular body, delivering an explosive gas mixture into the interiorof the sealed tubular body, then igniting the gas mixture and therebypro-. ducing a products of combustion pressure shock wave I the steps ofenclosing a tubular body within a shaped mold and sealing the ends ofthe tubular body, exhausting air from within the tubular body,delivering a combustible gas into the'interior of the sealed tubularbody, introducing a gas containing oxygen available for combustion intothe sealed tubular body with the combustible gas to form an explosivegas mixture, igniting the explosive gas mixture and thereby producing aproducts of combustion pressure shock wave which outwardly expands thetubular body to conform to the shape of the mold, exhausting theproducts of combustion from the reshaped tubular body, and then removingthe reshaped tubular body from the mold.

6. A method of reshaping tubular bodies comprising the steps ofenclosing a tubular body within a shaped mold and sealing the ends ofthe tubular body, separately delivering a combustible gas and a gascontaining oxygen available for combustion into the sealed tubular bodyto form an explosive gas mixture, igniting the explosive gas mixture andthereby producing a products of combustion pressure shock wave whichoutwardly expands the tubular body to conform to the shape of the mold,exhausting the products of combustion from the reshaped tubular body,and then removing the reshaped tubular body from the mold.

7. The method of claim 6 wherein the combustible gas is from the groupconsisting of hydrogen and hydro-carbons'.

8. The method of claim 6 wherein the combustible gas is hydrogen.

9. The method of claim 6 wherein the combustible gas is a hydro-carbon.

10. A method of forming a decoratively shaped can body comprising thesteps of forming a can body in the conventional manner, sealing the endsof the can body with the can body being within a mold, and thenintroducing an explosive gas mixture into the can body and igniting thesame to explosive reform the can body to the internal contour of themold.

11. The method of claim 10 wherein the sealing of at least one end ofthe can body is accomplished by securin a can end thereto in the normalmanner.

12. A method of forming a decoratively shaped can body comprising thesteps of forming a can body in the conventional manner, sealing the endsof the can body with the can body being within a mold, and thenintroducing an explosive gas mixture into the can body and igniting thesame to explosive reform the can body to the internal contour of themold, and then attaching can ends to the reformed can body in the normalmanner.

13. A method of forming a decoratively shaped container comprising thesteps of extruding a hollow container having a closed end in the normalmanner, and explosion reforming said container within a shaped mold tothe desired decorative shape.

14. A method of forming a decoratively shaped container comprising thesteps of extruding a thin walled plastic polymeric tubular member openat both ends, applying a metal end member to at least one end of thetubular member, and explosion reforming the tubular member within ashaped mold to the desired decorative shape.

, 1 lvalve for selective communication with said fluid line by saidvalve.

16. The apparatus of claim 15 wherein said other lines include anexhaust line, a combustible gas supply line, and an oxidizing agentsupply line.

17. The apparatus of claim 15 wherein said other lines include a vacuumline, an exhaust line, a combustible gas supply line, and an oxidizingagent supply line.

18. The apparatus of claim 15 together with means for energizing saidignition device in timed relation to the operation of said valve.

19. The apparatus of claim 15 wherein said support is configurated forthe simultaneous explosive reforming of an end member of a hollow objectclosing one end thereof.

20. A method'of reshaping tubular bodies comprising the steps ofenclosing a tubular body within a shaped mold and sealing the ends ofthe tubular body, exhausting air from within the tubular body,separately delivering under pressure a combustible gas from the groupconsisting of hydrogen and hydro-carbons and an oxidizing agent into thesealed tubular body to form an explosive gas mixture, igniting theexplosive gas mixture andthereby producing a products of combustionpressure shock wave which outwardly expands the tubular body to conformto the shape of the mold, exhausting the products of combustion from thereshaped tubular body, and then removing the reshaped tubular body fromthe mold.

12 I References Cited by the Examiner UNITED STATES PATENTS 939,70211/1909 Jones ll344 2,272,111 2/1942 Dove 133120 2,405,714 8/1946 Ryan83'-l77 2,892,733 6/1959 Gardner et a1.

2,935,038 5/1960 Chatten 113-44 FOREIGN PATENTS 742,458 12/ 1955 GreatBritain.

' OTHER REFERENCES The Tool and Manufacturing Engineer, pages 61-68,January 1962.

Advanced High Energy Rate Forming, Book II, book copyright 1962 byASTME, article relied on entitled Explosive Forming With Gas Mixtures,by Richard E. Lingen, copyright of article 1961, report No. SP62-02,pages 1-12. (Copy in Scientific Lib.)

The Tool and Manufacturing Engineer, pages 123 126, May 1961.

Materials in Design Engineering, pages 82-87, February 1959.

CHARLES W. LANHAM, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

1. A METHOD OF RESHAPING TUBULAR BODIES COMPRISING THE STEPS OFENCLOSING AN OPEN ENDED TUBULAR BODY WITHIN A SHAPED MOLD AND SEALINGTHE ENDS OF THE TUBULAR BODY, DELIVERING AN EXPLOSIVE GAS MIXTURE INTOTHE INTERIOR OF THE SEALED BODY, AND THEN IGNITING THE GAS MIXTURE AND